This quality control criterion consists in calculation of the maximal length of edges and diagonals of 2D mesh elements (triangles and quadrangles). For polygons the value is always zero.
To apply the Element Diameter 2D quality criterion to your mesh:
Display your mesh in the viewer.
Choose Controls > Face Controls > Element Diameter 2D or click "Element Diameter 2D" button in the toolbar.
Your mesh will be displayed in the viewer with its elements colored according to the applied mesh quality control criterion:
See Also a sample TUI Script of a Element Diameter 2D quality control operation.